From: Mark Wielaard <mjw@redhat.com>
Date: Wed, 18 Dec 2013 17:02:42 +0000 (+0100)
Subject: backends: Avoid type-punning issue in s390_set_initial_registers_tid.
X-Git-Tag: elfutils-0.158~29
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a3afdb212742e28c6d309ae919e81c52afb44542;p=platform%2Fupstream%2Felfutils.git

backends: Avoid type-punning issue in s390_set_initial_registers_tid.

Use union to avoid type-punning when assigning a double to a Dwarf_Word.
gcc complains otherwise. error: dereferencing type-punned pointer will
break strict-aliasing rules.

Signed-off-by: Mark Wielaard <mjw@redhat.com>
---

diff --git a/backends/ChangeLog b/backends/ChangeLog
index cb56d21..23329d0 100644
--- a/backends/ChangeLog
+++ b/backends/ChangeLog
@@ -1,3 +1,8 @@
+2013-12-18  Mark Wielaard  <mjw@redhat.com>
+
+	* 390_initreg.c (s390_set_initial_registers_tid): Use union
+	to avoid type-punning when assigning a double to a Dwarf_Word.
+
 2013-12-18  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	unwinder: s390 and s390x
diff --git a/backends/s390_initreg.c b/backends/s390_initreg.c
index 62a1531..8fc54bc 100644
--- a/backends/s390_initreg.c
+++ b/backends/s390_initreg.c
@@ -68,8 +68,19 @@ s390_set_initial_registers_tid (pid_t tid __attribute__ ((unused)),
   eu_static_assert (sizeof user_regs.regs.fp_regs.fprs[0]
 		    == sizeof dwarf_regs[0]);
   for (unsigned u = 0; u < 16; u++)
-    dwarf_regs[u] = *((const __typeof (dwarf_regs[0]) *)
-		      &user_regs.regs.fp_regs.fprs[u]);
+    {
+      // Store the double bits as is in the Dwarf_Word without conversion.
+      union
+	{
+	  double d;
+	  Dwarf_Word w;
+	} fpr = { .d = user_regs.regs.fp_regs.fprs[u] };
+      dwarf_regs[u] = fpr.w;
+    }
+   if (! setfunc (16, 16, dwarf_regs, arg))
+     return false;
+   dwarf_regs[0] = user_regs.regs.psw.addr;
+
   if (! setfunc (16, 16, dwarf_regs, arg))
     return false;
   dwarf_regs[0] = user_regs.regs.psw.addr;